Wrought superalloys

ABSTRACT

WROUGHT SUPERALLOY COMPOSITIONS POSSESSING HIGH STRENGHT, CORRSION RESISTANCE AND UTILITY AT MODERATE TEMPERTURES ARE PRODUCED BY ATOMIZING A MELT OF THE DESIRED COMPOSITION AND THEREAFTER CONSOLIDATING THE POWDERS BY EXTRUSION AND PRESSFORGING.

23, 17@ B. A. SWING ETAL 3,825,420

wRouGHT suPEnALLoYs Filed Aug. 21, 1972 Il D@ OON ll GNN i3d Ssang ummqxow 3,825,420 WROUGHT SUPERALLOYS Bruce A. Ewing and Frank J. Rizzo, Jr., Shelton, Conn., `i` assignors" to` Aveo Corporation, Stratford, Conn.

Filed Aug. 21, 1972, Ser. No. 282,510 L .II1f..Cl-VC2.2 19! 00 U.S. Cl. 75-171 9 Claims ABSTRACT oF THE DISCLOSURE VlfrollighvtY `superalloy Y compositions possessing high strength, corrosion'resistance and utility at moderate temperatures are produced by atomizing a melt of the desired composition and thereafter consolidating the powders by extrusion and pressforging.

This invention relates to wrought articles exhibiting a desirable combination of physical properties favorable to their use in compressor blade as well as compressor and turbine disc applications where alloy homogeneity, and high strength/density characteristics are of particular importance.

This invention is applicable to the following compositions in percent by weight.

.,containingnot Vmore than 200 p.p.m. oxygen, less than "0.089% nitrogen and less than 0.75% Fe, the balance being essentially Ni.

A more preferred range of compositions is as follows:

l`O2, N2, Fe as above, the balance being Ni.

Hafnium is lan optional constituent in these alloys.

` When present, the Ybenefits conferred by the HF are obtained when the hafnium content is between about 0.75 and 2.0%'by-wei`gh't`. f

"A 'Cast-alloys offt'heseV or'closely'ielated compositions are` described in-o'ur copending United States Patent Applica- 'n Filed nited States at@ 1s9,.733f oct. 15, 1971. 196-,799; j Nov. 5, 1971.1 243,418: Apr. 1o, 1972.

.-'The'f compositions "of this invention whensuitably procssed .into wrought articles achieve tine grain sizes and ompllet'e alloy homogeneity and exhibit uniform mechani-j 3,825,420 Patented July 23, 1974 cal properties. A fine dispersion of gamma prime Nia (Al, Ti) phase contributes to the excellent tensile and fatigue properties exhibited by the alloys in their wrought form which are significantly superior to these properties in the same articles when cast from a melt of the alloy.

In order to produce articles which exhibit higher tensile strength and better fatigue properties than those of the cast superalloys of the above noted applications, wrought articles of similar compositions may be produced by the following procedure:

(l) Form a melt of desired alloy composition;

(2) Atomize the melt to produce powder particles; (3) Consolidate the particles to form a billet; (4) Work the billet to to produce a wrought article.

Preferred procedures for electing each of these Ysteps are as follows:

1. Atomization The molten compositions are atomized with gas or by other suitable known techniques in which the material is protected from the atmosphere to produce powder particles. In the examples which follow, the atomization process consisted of vacuum induction melting, back-filling of the melting chamber with a positive pressure of argon and atomizing by gravity feeding liquid metal through a ceramic nozzle. As the metal passed out the bottom of the nozzle a jet of argon impinged on the molten stream and atomized the material which was collected in an argon filled chamber below.

After atomization, the powder was classified according to particle size. Analysis showed that about 20 percent of the entire powder yield was +100 mesh size, 45 percent -100 +325 mesh size and 35 percent -325 mesh size. Typical oxygen contents of the powders produced were 50 p.p.m. for the -20 +100 mesh particles, 80 p.p.m. for the -100 +325 mesh particles.

2. Consolidation t of the powders and was utilized in the Examples described in this application.

Of the alloy powder produced, only the -100 mesh particles were used for canning preliminary to extrusion. The cans utilized consisted of stainless steel tubes, typically 4% inches inside diameter and 55/8 inches outside diameter, each of which had a stainless steel plug approximately two inches thick electron beam welded to one end. The cans lwere yibrated as the powder was added to achieve the greatest possible tap density (e.g., to 70 percent). Once the cans were illed with powder, two inch thick stainless steel plugs containinghollow stems, for evacuation were electron beam welded to the open ends. The cans were evacuated to 10F4 microns. During evacuation they were induction'v heated to approximately 1000 F.

to remove adsorbed gases. Sealing wasperformed byzpeening the evacuated tube and TIG welding` Extrusion of the cans was performed at temperatures of 2000 F. to

2.050" F. and ratios of from 4:1I to 10:1. Oxygen analysis showed the extruded billets to contain 1 generally less than `10U-p.p.m. Examination of the specimens representative of these bars'revealed a uniform structure; lsmall MC-type carbides Wererandomly distributed throughout anda large amount'of gamma primepre'cip'itate wasl present. Grain size was extremely fine being between Atwo and four microns in diameter (ASTM No. 14).

fTABLEY Cycle Fatigue Propertiesl* for vAlloy v'VIII TALE III-,Continued -CyclesfTo Failure 9001F. Low

Load (P si 230 220 'Y A210 200 190 eat number 1.0 Frequency: 2.0 c.p.s. I

*Conditions of Tests .A: Ratio:

I: Heat treatment Load controlled The superiority of the powder alloy over the convenional D979 alloy is apparent in FIG. 1.

When tested for stress" rupture'the results reported in Table IV were obtained.

The properties of the wrought alloys of this invention are superior to the properties of otherwise similar alloys which were cast rather than wrought. This can be seen TABLE IV by comparing the properties reported in Table II, with Stress rupture results 1,200 F./150 K S.i.

o similar tests in the above noted applications, the dis- 1'400 FJBrKS'' closures of which are intended to be incorporated by reference, and the results in Table VI.

Life EL Life EL (hrs.) (percent) (hrs) (percent) Heat number TABLE VI.-COMPARISON OF ROOM TEMPERATURE TENSILE PROPERTIES HHIIIIAA Tensile 0.2% yield Strength strength Percent (K s.i.) (K si.) elong.

Xx (With hainium)-.

Prior art (cast) 2.

III 1 (without hainium)- containing not more than 200 p.p.m. oxygen, less than 65 0.089% nitrogen and less than 0.75% Fe, the balance said powder metallurgy processing comprising at least the following:

""""`"'"I'"' being essentially Ni;

Mmmm.

IIII

consolidating particles of said alloy composition to 5 70 form a billet; and 5 thereafter hot forging said billet to produce Said lNot measured-Specimen stuck in grips. WI'Ollght article.

2. A compressor disc formed of the alloy of Claim 1. 3. A turbine disc formed of the alloy of Claim 1.

When tested for low cycle fatigue strength, the results reported in Table V were obtained.

75 4. A compressor blade formed of the alloy of Claim 1.

O2, N2, Fe as above, the balance being Ni.

6. A compressor disc formed of the alloy of Claim 5. 7. A turbine disc formed of the alloy of'Claim 5.

UNLTED S'iA'llS IA'llflN'l OFFICE @ERTIFICATE OF CORRECTION Patent No. 3,825,420 Dated July 23, 1974 nventorfs) Bruce A. Ewing and Frank J.. Rizzo, Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In eolumn 5, Table III Continued, Heat number VII, the

second item in column "RA" should be changed from "26.6" to 26. 3 the fourth item should be changed from "7. 3" to 7. 8 and the fifth item "8" should be deleted.

Column 6, line 4.4, after "super-alloy" insert turbine or compressor component Column 6, line 72, delete "article" and substitute turbine or compressor component from said billet Column 7, line'l, delete. "alloys" and substitute articles A Signed and sealed this 5th day of November 1974.

MQOY M. GlBSON JR. C. MARSHALL DANN meeting Officer Commissioner of Patents UNH'ED SiA'llS IA'lllN'l OFFICE @ERTIMQATE l" CORRECTION Patent No. 3,825,420 Bnted July 23, 1974 nventorsb Bruce A. Ewing and Frank J. Rizzo, Jr.

It is certified that error appears in the above-identified patent and that said Lettera Patent are hereby corrected as shown below:

In column 5, Table III Continued, Heat number VII, the

second item in column "RA" should be changed from "26.6" to 26. 3 the fourth item should be changed from "7. 3" to 7. 8 and the fifth item "8" should be deleted.

Calumn 6, line 44, after "superalloy" insert turbine or compressor component -z Column 6, line 72,7 delete "article" and substitute turbine or compressor component from said billet Column 7, line l, delete* "alloys" and substitute articles signed ma sealed this 5th day @f November 19M.

"mmm

-Attest;v

Mem M. @ISDN Y C. MARSHALL DANN arresting; @Miner Commissioner of Patents 

